Macroporous polyvinyl alcohol-formaldehyde-silicon composite sponges with designed structure for high-efficiency water-in-oil emulsion separation

Macroporous materials with suitable pore structure and surface composition have demonstrated their advancing applications in absorption, adsorption, and separation. In this contribution, two types of macroporous polyvinyl alcohol-formaldehyde (PVFs) based composite sponges, stearoyl chlorides modified polyvinyl alcohol/PVF (PVA/PVF-CH) and octadecyltrimethoxysilane modified PVA/PVF (PVA/PVF-Si) are designed and synthesized through the secondary crosslinking reaction between the hydroxyl groups in PVA and PVF with formaldehyde, and subsequently covalently bonding the long-alkyl chains into the network of the composite sponge. Basic characterizations confirm PVA/PVF-CH and PVA/PVF-Si composite sponges exhibit the open-cell structure as original PVFs with porosity up to 80.1%, hydrophobic networks, and narrow pore size distribution (5 mu m to 60 mu m). Notably, the PVA/PVF-Si, possessing the smallest average pore size (14.4 mu m), exhibits ignorable swelling performances in a wide range of organic solvents and excellent mechanical properties and separation properties for oil from water-in-oil emulsion with separation efficiency and flux up to 99.99% and 7.65 x 104 L m ? 2h 1bar ? 1 as compared to PVA/PVF-CH, respectively. Those features indicate that PVA/PVF-Si composite sponges can be desirable for emulsion separation.